The invention relates to a condensation dryer with a housing, comprising a wall area forming a rear side and with a process air circuit for circulating process air, said circuit having a section outside the housing and running along the wall area and being otherwise located inside the housing, there being located in the circuit a fan for circulating the process air and a drying chamber for holding objects to be dried, wherein the section is covered by a hood that is placed in sealing fashion on the wall area.
Such a condensation dryer originates from WO 2006/122840 A1. The tumble dryer described there has an electrical heater for the air used to dry laundry, the so-called process air and the process air is guided through a flow channel to the heater, with the flow channel being attached as a U-shaped profile on the outside to a rear side of a housing of the dryer and being covered by a hood. As a result of the flowing process air being covered twice, the loss of heat is reduced and acoustic insulation to counter noises caused by the flowing process air is improved.
In a condensation dryer, process air is routed by a fan via a heater into a drum containing damp items of laundry as a drying chamber. The hot air absorbs moisture from the items of laundry to be dried. After passing through the drum, the then moist process air is routed into a heat exchanger, upstream of which is generally connected a lint filter. The moist process air is cooled down in this heat exchanger, with the moisture carried along as steam being condensed and collecting under the heat exchanger in liquid form. The thus dehumidified process air once again flows to the heater and from there to the drum in order to absorb further moisture from the items of laundry.
This drying process is very energy-intensive, since the heat, which is extracted from the cold air flow when cooling the process air in the heat exchanger, is lost from the process in terms of energy. The use of a heat pump can significantly reduce this energy loss. In the case of a condensation dryer equipped with a heat pump, the cooling of the warm process air laden with moisture essentially takes place in a heat sink of the heat pump. This may be embodied as an evaporator, where the transmitted heat is used to evaporate a refrigerant circulating in a closed circuit. The refrigerant in the heat pump which is evaporated on account of heating is fed via a compressor to a condenser which functions as a heat source in the heat pump, where, on account of the condensation of the gaseous refrigerant, heat is released, which is used to heat the process air prior to entry into the drum. In this way the heat source adopts the function of the heater in the simple condensation dryer. The steam contained in the moist process air condenses in the heat sink. The condensed water is then generally collected in a suitable container.
A tumble dryer with a heat pump is described in DE 40 23 000 C2, in which a supply air opening is arranged in the process air channel between the heat source and the heat sink, said supply air opening being sealable with a controllable sealing facility.
A tumble dryer with a heat pump originates from WO 2008/107266 A1 and WO 2008/119611 A1. A heat pump in a tumble dryer is generally embodied as a compact unit and arranged below the drum for the items of laundry to be dried. An electrical heater for the process air is not present.
DE 20 2007 000 648 U1 discloses a tumble dryer with a drum for receiving laundry to be dried, a process air circuit for guiding process air and a heat pump circuit with a condenser, an evaporator, a throttle element and a compressor, with an additional heat exchanger being arranged in the heat pump circuit between the condenser and the throttle element. A tumble dryer is shown in FIGS. 2 to 5, said tumble dryer having a drum which can be loaded from the front, it being possible to rotate said drum about a horizontal axis. The process air passes from the drum interior through a filter or several filters in the appliance door, and then passes through the evaporator, the condenser, the fan and an optional additional heater and is guided through holes in the rear wall of the drum back into the drum. In order to guide the process air in the region of the evaporator and the condenser, these are arranged in a channel, which is formed by a channel housing. An air routing molded part which is arranged above the additional heat exchanger is used here to guide air in the region of the additional heat exchanger.